影响晶圆凸起网板印刷效果的基本设计事项

Fundamental Design Issues Affecting the Success of Stencil Printing for Wafer Bumping

业界现有数种技术可用于在晶圆的焊垫上涂敷焊料混合物,这种工艺称之为晶圆凸起。大多数此类技术需要昂贵的专门设备,不过,采用网板印刷进行晶圆凸起加工正逐渐成为一种可节省成本的大批量生产替代方案,而且广受欢迎。但随着I?O数目增加和间距不断缩小,这种使用网板在焊点上印刷焊膏的方法变得更有挑战性,而且,对于与之匹配的材料(如焊膏、网板等)和工艺设计水准的要求也大大提高。因此,研发人员继续进行研究,以便更好地了解这些细节,从而达到进一步改进网板印刷晶圆凸起工艺之目的。

Several techniques can be used to apply a solder alloy to the pad sites on a wafer, a process known as wafer bumping. While most of these techniques require high-priced, specialized equipment, the use of stencil printing for wafer bumping offers an attractive, cost-saving alternative for high-volume production. Standard surface mount assembly equipment can be used in a contract assembly house environment at a much lower cost. In the few second it takes for the printhead to distribute solder paste across a stencil, hundreds of thousands of pads can be bumped simultaneously. This method does require the utilization of unique design guidelines tailored for each application. In addition, specific equipment, materials and process instructions need to be followed to establish a robust, high-yield wafer bumping print and reflow procedure.